Lubricating oil additive and lubricating oil composition containing same

ABSTRACT

A molybdated succinimide complex is disclosed which is prepared by a process comprising (a) reacting a succinimide of a polyamine of formula I: 
                         
wherein R is a hydrocarbon radical having a number average molecular weight of about 500 to about 5,000, a and b are independently 2 or 3, and x is 0 to 10, with an ethylenically unsaturated carboxylic acid or anhydride thereof, in a charge mole ratio of the ethylenically unsaturated carboxylic acid or anhydride thereof to the succinimide of formula I of about 0.9:1 to about 1.05:1; and (b) reacting the succinimide product of step (a) with an acidic molybdenum compound. Also disclosed is a lubricating oil composition containing at least (a) a major amount of a base oil of lubricating viscosity and (b) a minor amount of the molybdated succinimide complex.

PRIORITY

This application is a continuation of U.S. patent application Ser. No.12/215,739, filed Jun. 30, 2008 now U.S. Pat. No. 8,022,023, thecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention generally relates to a lubricating oil additiveand lubricating oil composition containing same.

2. Description of the Related Art

In general, organic molybdenum compounds are known to improve thelubricating properties of engine oils. For example, molybdenumdithiocarbamates are typically employed for the reduction of friction.The molybdenum dithiocarbamates, however, contain sulfur and slowly losethe ability to reduce friction unless an alternate sulfur source ispresent in the lubricating oil. Another example of organic molybdenumcompounds are sulfurized molybdenum polyisobutenyl succinimide complexeswhich are used to mediate wear, reduce friction, and/or controloxidation. See, e.g., U.S. Pat. Nos. 4,259,194; 4,265,773; 4,283,295;4,285,822; and 6,962,896 and U.S. Patent Application Publication No.2005/0209111. Problems associated with the use of sulfur in alubricating oil are that sulfur can be incompatible with emissioncontrol devices and can result in corrosion problems.

U.S. Pat. Nos. 4,357,149 and 4,500,439 disclose molybdated C₁₅-C₂₀alkenyl succinimides. In Example XI of both of these patents, amolybdated succinimide is prepared by reacting a C₁₅-C₂₀ alkenylsuccinic anhydride with triethylene tetramine followed by treatment witha molybdic acid solution.

Russian Patent No. 2201433 discloses a molybdated succinimidepost-treated with maleic anhydride as an additive for motor oils used ininternal combustion engines. Russian Patent No. 2201433 furtherdiscloses that the additives are prepared by reacting an alkenylsuccinimide of polyethylene polyamine with ammonium molybdate in thepresence of water as a promoter and then reacting the resulting productwith maleic anhydride taken in amounts of 0.2 to 1.0 mole per 1 mole ofalkenyl succinimide of polyethylene polyamine. All of the examplesdisclosed in Russian Patent No. 2201433 employ a high molecular weightpolyisobutenyl (950 M.W.) succinic anhydride (PIBSA) in preparing thealkenyl succinimide of polyethylene polyamine.

Accordingly, it would be desirable to develop improvedmolybdenum-containing lubricating oil compositions which exhibitimproved friction reduction, and wear and oxidation inhibition.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, a molybdatedsuccinimide complex prepared by a process which comprises (a) reacting asuccinimide of a polyamine of formula I:

wherein R is a hydrocarbon radical having a number average molecularweight of about 500 to about 5,000, a and b are independently 2 or 3,and x is 0 to 10, with an ethylenically unsaturated carboxylic acid oranhydride thereof, in a charge mole ratio of the ethylenicallyunsaturated carboxylic acid or anhydride thereof to the succinimide offormula I of about 0.9:1 to about 1.05:1; and (b) reacting thesuccinimide product of step (a) with an acidic molybdenum compound.

In accordance with a second embodiment of the present invention, aprocess for preparing a molybdated succinimide complex is provided whichcomprises (a) reacting a succinimide of a polyamine of formula I:

wherein R, a, b and x have the aforestated meanings, with anethylenically unsaturated carboxylic acid or anhydride thereof, in acharge mole ratio of the ethylenically unsaturated carboxylic acid oranhydride thereof to the succinimide of formula I of about 0.9:1 toabout 1.05:1; and (b) reacting the succinimide product of step (a) withan acidic molybdenum compound.

In accordance with a third embodiment of the present invention, alubricating oil composition is provided which comprises (a) a majoramount of a base oil of lubricating viscosity; and (b) a minor amount ofa molybdated succinimide complex prepared by a process which comprises(i) reacting a succinimide of a polyamine of formula I:

wherein R, a, b and x have the aforestated meanings, with anethylenically unsaturated carboxylic acid or anhydride thereof, in acharge mole ratio of the ethylenically unsaturated carboxylic acid oranhydride thereof to the succinimide of formula I of about 0.9:1 toabout 1.05:1; and (ii) reacting the succinimide product of step (i) withan acidic molybdenum compound.

In accordance with a fourth embodiment of the present invention, thereis provided a method of operating an internal combustion engine whichcomprises operating the internal combustion engine with a lubricatingoil composition comprising (a) a major amount of a base oil oflubricating viscosity and (b) a minor amount of a molybdated succinimidecomplex prepared by a process which comprises (i) reacting a succinimideof a polyamine of formula I:

wherein R, a, b and x have the aforestated meanings, with anethylenically unsaturated carboxylic acid or anhydride thereof, in acharge mole ratio of the ethylenically unsaturated carboxylic acid oranhydride thereof to the succinimide of formula I of about 0.9:1 toabout 1.05:1; and (ii) reacting the succinimide product of step (i) withan acidic molybdenum compound.

In accordance with a fifth embodiment of the present invention, anadditive package composition or concentrate is provided comprising (a)about 20 to about 80 weight percent of an inert organic diluent and (b)one or more of a molybdated succinimide complex prepared by a processwhich comprises (i) reacting a succinimide of a polyamine of formula I:

wherein R, a, b and x have the aforestated meanings, with anethylenically unsaturated carboxylic acid or anhydride thereof, in acharge mole ratio of the ethylenically unsaturated carboxylic acid oranhydride thereof to the succinimide of formula I of about 0.9:1 toabout 1.05:1; and (ii) reacting the succinimide product of step (i) withan acidic molybdenum compound.

The molybdated succinimide complex of the present inventionadvantageously provides high friction reduction, and wear andoxidation-corrosion inhibition when incorporated into a lubricating oilcomposition and used in an internal combustion engine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In general, a molybdated succinimide complex of the present invention isprepared by a process which involves at least (a) reacting a succinimideof a polyamine of formula I:

wherein R is a hydrocarbon radical having a number average molecularweight of about 500 to about 5,000, preferably a number averagemolecular weight of about 700 to about 2,500 and more preferably anumber average molecular weight of about 710 to about 1,100; a and b areindependently 2 or 3; and x is 0 to 10, preferably 1 to 6 and morepreferably 2 to 5, with an ethylenically unsaturated carboxylic acid oranhydride thereof, in a charge mole ratio of the ethylenicallyunsaturated carboxylic acid or anhydride thereof to the succinimide offormula I of about 0.9:1 to about 1.05:1; and (b) reacting thesuccinimide product of step (a) with an acidic molybdenum compound. Inone embodiment, R is an alkyl or alkenyl group. In another embodiment, Ris a polyalkenyl group. A preferred polyalkenyl group is apolyisobutenyl group.

In step (a), a succinimide of formula I:

wherein R, a, b and x have the aforestated meanings, is reacted with anethylenically unsaturated carboxylic acid in a charge mole ratio of theethylenically unsaturated carboxylic acid or anhydride thereof to thesuccinimide of formula I of about 0.9:1 to about 1.05:1. The startingsuccinimide of formula I can be obtained by reacting an anhydride offormula II:

wherein R has the aforestated meaning with a polyamine. The anhydride offormula II is either commercially available from such sources as, forexample, Sigma Aldrich Corporation (St. Louis, Mo., U.S.A.), or can beprepared by any method well known in the art.

Suitable polyamines for use in preparing the succinimide of formula Iare polyalkylene polyamines, including polyalkylene diamines. Suchpolyalkylene polyamines will typically contain about 2 to about 12nitrogen atoms and about 2 to 24 carbon atoms. Particularly suitablepolyalkylene polyamines are those having the formula: H₂N—(R¹NH)_(c)—Hwherein R¹ is a straight- or branched-chain alkylene group having 2 or 3carbon atoms and c is 1 to 9. Representative examples of suitablepolyalkylene polyamines include ethylenediamine, diethylenetriamine,triethylenetetraamine, tetraethylenepentamine and mixtures thereof. Mostpreferably, the polyalkylene polyamine is tetraethylenepentamine.

Many of the polyamines suitable for use in the present invention arecommercially available and others may be prepared by methods which arewell known in the art. For example, methods for preparing amines andtheir reactions are detailed in Sidgewick's “The Organic Chemistry ofNitrogen”, Clarendon Press, Oxford, 1966; Noller's “Chemistry of OrganicCompounds”, Saunders, Philadelphia, 2nd Ed., 1957; and Kirk-Othmer's“Encyclopedia of Chemical Technology”, 2nd Ed., especially Volume 2, pp.99 116.

Generally, the anhydride of formula II is reacted with the polyamine ata temperature of about 130° C. to about 220° C. and preferably fromabout 145° C. to about 175° C. The reaction can be carried out under aninert atmosphere, such as nitrogen or argon. The amount of anhydride offormula II employed in the reaction can range from about 30 to about 95wt. % and preferably from about 40 to about 60 wt. %, based on the totalweight of the reaction mixture.

Suitable ethylenically unsaturated carboxylic acids or their anhydridesinclude ethylenically unsaturated monocarboxylic acids or theiranhydrides, ethylenically unsaturated dicarboxylic acids or theiranhydrides and the like and mixtures thereof. Useful monocarboxylicacids or their anhydrides include, but are not limited to, acrylic acid,methacrylic acid, and the like and mixtures thereof Useful ethylenicallyunsaturated dicarboxylic acids or their anhydrides include, but are notlimited to, fumaric acid, maleic anhydride, mesaconic acid, citraconicacid, citraconic anhydride, itaconic acid, itaconic anhydride, and thelike and mixtures thereof. A preferred ethylenically unsaturatedcarboxylic acid or anhydride thereof is maleic anhydride or a derivativethereof. This and similar anhydrides bond onto the succinimide startingcompound to provide a carboxylic acid functionality. The treatment ofthe succinimide of formula I with the ethylenically unsaturatedcarboxylic acid or anhydrides thereof advantageously allows for asufficient amount of the molybdenum compound to be incorporated into thecomplex.

Generally, the ethylenically unsaturated carboxylic acid or itsanhydride is heated to a molten condition at a temperature in the rangeof from about 50° C. to about 100° C. and is thereafter mixed with thesuccinimide of formula I.

The molybdenum compounds used to prepare the molybdated succinimidecomplex of the present invention are acidic molybdenum compounds orsalts of acidic molybdenum compounds. Generally, these molybdenumcompounds are hexavalent. Representative examples of suitable molybdenumcompounds include, but are not limited to, molybdenum oxide, molybdenumtrioxide, molybdic acid, ammonium molybdate, sodium molybdate, potassiummolybdate and other alkaline metal molybdates and other molybdenum saltssuch as hydrogen salts, e.g., hydrogen sodium molybdate, MoOCl₄,MoO₂Br₂, Mo₂O₃Cl₆, or similar acidic molybdenum compounds. Preferredacidic molybdenum compounds are molybdenum trioxide, molybdic acid,ammonium molybdate, and alkali metal molybdates. Particularly preferredis molybdenum trioxide.

In step (b), a mixture of the succinimide product of step (a) and acidicmolybdenum compound is prepared with or without a diluent. A diluent isused, if necessary, to provide a suitable viscosity for easy stirring.Suitable diluents are lubricating oils and liquid compounds containingonly carbon and hydrogen. If desired, ammonium hydroxide may also beadded to the reaction mixture to provide a solution of ammoniummolybdate

Generally, the reaction mixture is heated at a temperature less than orequal to about 100° C. and preferably from about 80° C. to about 100° C.until the molybdenum is sufficiently reacted. The reaction time for thisstep is typically in the range of from about 15 minutes to about 5 hoursand preferably from about 1 to about 2 hours. The molar ratio of themolybdenum compound to the succinimide product of step (a) is about0.1:1 to about 2:1, preferably from about 0.5:1 to about 1.5:1 and mostpreferably about 1:1. Any water present following the reaction of themolybdenum compound and succinimide product of step (a) can be removedby heating the reaction mixture to a temperature greater than about 100°C., and preferably from about 120° C. to about 160° C.

Another embodiment of the present invention is directed to a lubricatingoil composition containing at least (a) a major amount of a base oil oflubricating viscosity; and (b) a minor amount of the molybdatedsuccinimide complex of this invention which is useful as a lubricatingoil additive. The lubricating oil compositions can be prepared byadmixing, by conventional techniques, an appropriate amount of thelubricating oil additive of this invention with a base oil oflubricating viscosity. The selection of the particular base oil dependson the contemplated application of the lubricant and the presence ofother additives. Generally, a minor amount of the molybdated succinimidecomplex of this invention will vary from about 0.001 to about 10% byweight and preferably from about 0.5 to about 2% by weight, based on thetotal weight of the lubricating oil composition.

The base oil of lubricating viscosity for use in the lubricating oilcompositions of this invention is typically present in a major amount,e.g., an amount of greater than 50 wt. %, preferably greater than about70 wt. %, more preferably from about 80 to about 99.5 wt. % and mostpreferably from about 85 to about 98 wt. %, based on the total weight ofthe composition. The expression “base oil” as used herein shall beunderstood to mean a base stock or blend of base stocks which is alubricant component that is produced by a single manufacturer to thesame specifications (independent of feed source or manufacturer'slocation); that meets the same manufacturer's specification; and that isidentified by a unique formula, product identification number, or both.The base oil for use herein can be any presently known orlater-discovered base oil of lubricating viscosity used in formulatinglubricating oil compositions for any and all such applications, e.g.,engine oils, marine cylinder oils, functional fluids such as hydraulicoils, gear oils, transmission fluids, etc. Additionally, the base oilsfor use herein can optionally contain viscosity index improvers, e.g.,polymeric alkylmethacrylates; olefinic copolymers, e.g., anethylene-propylene copolymer or a styrene-butadiene copolymer; and thelike and mixtures thereof.

As one skilled in the art would readily appreciate, the viscosity of thebase oil is dependent upon the application. Accordingly, the viscosityof a base oil for use herein will ordinarily range from about 2 to about2000 centistokes (cSt) at 100° Centigrade (C). Generally, individuallythe base oils used as engine oils will have a kinematic viscosity rangeat 100° C. of about 2 cSt to about 30 cSt, preferably about 3 cSt toabout 16 cSt, and most preferably about 4 cSt to about 12 cSt and willbe selected or blended depending on the desired end use and theadditives in the finished oil to give the desired grade of engine oil,e.g., a lubricating oil composition having an SAE Viscosity Grade of 0W,0W-20, 0W-30, 0W-40, 0W-50, 0W-60, 5W, 5W-20, 5W-30, 5W-40, 5W-50,5W-60, 10W, 10W-20, 10W-30, 10W-40, 10W-50, 15W, 15W-20, 15W-30 or15W-40. Oils used as gear oils can have viscosities ranging from about 2cSt to about 2000 cSt at 100° C.

Base stocks may be manufactured using a variety of different processesincluding, but not limited to, distillation, solvent refining, hydrogenprocessing, oligomerization, esterification, and refining. Rerefinedstock shall be substantially free from materials introduced throughmanufacturing, contamination, or previous use. The base oil of thelubricating oil compositions of this invention may be any natural orsynthetic lubricating base oil. Suitable hydrocarbon synthetic oilsinclude, but are not limited to, oils prepared from the polymerizationof ethylene or from the polymerization of 1-olefins to provide polymerssuch as polyalphaolefin or PAO oils, or from hydrocarbon synthesisprocedures using carbon monoxide and hydrogen gases such as in aFischer-Tropsch process. For example, a suitable base oil is one thatcomprises little, if any, heavy fraction; e.g., little, if any, lube oilfraction of viscosity 20 cSt or higher at 100° C.

The base oil may be derived from natural lubricating oils, syntheticlubricating oils or mixtures thereof. Suitable base oil includes basestocks obtained by isomerization of synthetic wax and slack wax, as wellas hydrocracked base stocks produced by hydrocracking (rather thansolvent extracting) the aromatic and polar components of the crude.Suitable base oils include those in all API categories I, II, III, IVand V as defined in API Publication 1509, 14th Edition, Addendum I, Dec.1998. Group IV base oils are polyalphaolefins (PAO). Group V base oilsinclude all other base oils not included in Group I, II, III, or IV.Although Group II, III and IV base oils are preferred for use in thisinvention, these base oils may be prepared by combining one or more ofGroup I, II, III, IV and V base stocks or base oils.

Useful natural oils include mineral lubricating oils such as, forexample, liquid petroleum oils, solvent-treated or acid-treated minerallubricating oils of the paraffinic, naphthenic or mixedparaffinic-naphthenic types, oils derived from coal or shale, animaloils, vegetable oils (e.g., rapeseed oils, castor oils and lard oil),and the like.

Useful synthetic lubricating oils include, but are not limited to,hydrocarbon oils and halo-substituted hydrocarbon oils such aspolymerized and interpolymerized olefins, e.g., polybutylenes,polypropylenes, propylene-isobutylene copolymers, chlorinatedpolybutylenes, poly(1-hexenes), poly(1-octenes), poly(1-decenes), andthe like and mixtures thereof; alkylbenzenes such as dodecylbenzenes,tetradecylbenzenes, dinonylbenzenes, di(2-ethylhexyl)-benzenes, and thelike; polyphenyls such as biphenyls, terphenyls, alkylated polyphenyls,and the like; alkylated diphenyl ethers and alkylated diphenyl sulfidesand the derivative, analogs and homologs thereof and the like.

Other useful synthetic lubricating oils include, but are not limited to,oils made by polymerizing olefins of less than 5 carbon atoms such asethylene, propylene, butylenes, isobutene, pentene, and mixturesthereof. Methods of preparing such polymer oils are well known to thoseskilled in the art.

Additional useful synthetic hydrocarbon oils include liquid polymers ofalpha olefins having the proper viscosity. Especially useful synthetichydrocarbon oils are the hydrogenated liquid oligomers of C₆ to C₁₂alpha olefins such as, for example, 1-decene trimer.

Another class of useful synthetic lubricating oils include, but are notlimited to, alkylene oxide polymers, i.e., homopolymers, interpolymers,and derivatives thereof where the terminal hydroxyl groups have beenmodified by, for example, esterification or etherification. These oilsare exemplified by the oils prepared through polymerization of ethyleneoxide or propylene oxide, the alkyl and phenyl ethers of thesepolyoxyalkylene polymers (e.g., methyl poly propylene glycol etherhaving an average molecular weight of 1,000, diphenyl ether ofpolyethylene glycol having a molecular weight of 500-1000, diethyl etherof polypropylene glycol having a molecular weight of 1,000-1,500, etc.)or mono- and polycarboxylic esters thereof such as, for example, theacetic esters, mixed C₃-C₈ fatty acid esters, or the C₁₃ oxo aciddiester of tetraethylene glycol.

Yet another class of useful synthetic lubricating oils include, but arenot limited to, the esters of dicarboxylic acids e.g., phthalic acid,succinic acid, alkyl succinic acids, alkenyl succinic acids, maleicacid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipicacid, linoleic acid dimer, malonic acids, alkyl malonic acids, alkenylmalonic acids, etc., with a variety of alcohols, e.g., butyl alcohol,hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol,diethylene glycol monoether, propylene glycol, etc. Specific examples ofthese esters include dibutyl adipate, di(2-ethylhexyl)sebacate,di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecylazelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the2-ethylhexyl diester of linoleic acid dimer, the complex ester formed byreacting one mole of sebacic acid with two moles of tetraethylene glycoland two moles of 2-ethylhexanoic acid and the like.

Esters useful as synthetic oils also include, but are not limited to,those made from carboxylic acids having from about 5 to about 12 carbonatoms with alcohols, e.g., methanol, ethanol, etc., polyols and polyolethers such as neopentyl glycol, trimethylol propane, pentaerythritol,dipentaerythritol, tripentaerythritol, and the like.

Silicon-based oils such as, for example, polyalkyl-, polyaryl-,polyalkoxy- or polyaryloxy-siloxane oils and silicate oils, compriseanother useful class of synthetic lubricating oils. Specific examples ofthese include, but are not limited to, tetraethyl silicate,tetra-isopropyl silicate, tetra-(2-ethylhexyl) silicate,tetra-(4-methyl-hexyl)silicate, tetra-(p-tert-butylphenyl)silicate,hexyl-(4-methyl-2-pentoxy)disiloxane, poly(methyl)siloxanes,poly(methylphenyl)siloxanes, and the like. Still yet other usefulsynthetic lubricating oils include, but are not limited to, liquidesters of phosphorous containing acids, e.g., tricresyl phosphate,trioctyl phosphate, diethyl ester of decane phosphionic acid, etc.,polymeric tetrahydrofurans and the like.

The lubricating oil may be derived from unrefined, refined and rerefinedoils, either natural, synthetic or mixtures of two or more of any ofthese of the type disclosed hereinabove. Unrefined oils are thoseobtained directly from a natural or synthetic source (e.g., coal, shale,or tar sands bitumen) without further purification or treatment.Examples of unrefined oils include, but are not limited to, a shale oilobtained directly from retorting operations, a petroleum oil obtaineddirectly from distillation or an ester oil obtained directly from anesterification process, each of which is then used without furthertreatment. Refined oils are similar to the unrefined oils except theyhave been further treated in one or more purification steps to improveone or more properties. These purification techniques are known to thoseof skill in the art and include, for example, solvent extractions,secondary distillation, acid or base extraction, filtration,percolation, hydrotreating, dewaxing, etc. Rerefined oils are obtainedby treating used oils in processes similar to those used to obtainrefined oils. Such rerefined oils are also known as reclaimed orreprocessed oils and often are additionally processed by techniquesdirected to removal of spent additives and oil breakdown products.

Lubricating oil base stocks derived from the hydroisomerization of waxmay also be used, either alone or in combination with the aforesaidnatural and/or synthetic base stocks. Such wax isomerate oil is producedby the hydroisomerization of natural or synthetic waxes or mixturesthereof over a hydroisomerization catalyst.

Natural waxes are typically the slack waxes recovered by the solventdewaxing of mineral oils; synthetic waxes are typically the wax producedby the Fischer-Tropsch process.

The lubricating oil compositions of the present invention may alsocontain other conventional additives for imparting auxiliary functionsto give a finished lubricating oil composition in which these additivesare dispersed or dissolved. For example, the lubricating oilcompositions can be blended with antioxidants, anti-wear agents,detergents such as metal detergents, rust inhibitors, dehazing agents,demulsifying agents, metal deactivating agents, friction modifiers, pourpoint depressants, antifoaming agents, co-solvents, packagecompatibilisers, corrosion-inhibitors, ashless dispersants, dyes,extreme pressure agents and the like and mixtures thereof. A variety ofthe additives are known and commercially available. These additives, ortheir analogous compounds, can be employed for the preparation of thelubricating oil compositions of the invention by the usual blendingprocedures.

Examples of antioxidants include, but are not limited to, aminic types,e.g., diphenylamine, phenyl-alpha-napthyl-amine,N,N-di(alkylphenyl)amines; and alkylated phenylene-diamines; phenolicssuch as, for example, BHT, sterically hindered alkyl phenols such as2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol and2,6-di-tert-butyl-4-(2-octyl-3-propanoic) phenol; and mixtures thereof.

Examples of ashless dispersants include, but are not limited to,polyalkylene succinic anhydrides; non-nitrogen containing derivatives ofa polyalkylene succinic anhydride; a basic nitrogen compound selectedfrom the group consisting of succinimides, carboxylic acid amides,hydrocarbyl monoamines, hydrocarbyl polyamines, Mannich bases,phosphonoamides, and phosphoramides; triazoles, e.g., alkyltriazoles andbenzotriazoles; copolymers which contain a carboxylate ester with one ormore additional polar function, including amine, amide, imine, imide,hydroxyl, carboxyl, and the like, e.g., products prepared bycopolymerization of long chain alkyl acrylates or methacrylates withmonomers of the above function; and the like and mixtures thereof Thederivatives of these dispersants, e.g., borated dispersants such asborated succinimides, may also be used.

Examples of rust inhibitors include, but are not limited to, nonionicpolyoxyalkylene agents, e.g., polyoxyethylene lauryl ether,polyoxyethylene higher alcohol ether, polyoxyethylene nonylphenyl ether,polyoxyethylene octylphenyl ether, polyoxyethylene octyl stearyl ether,polyoxyethylene oleyl ether, polyoxyethylene sorbitol monostearate,polyoxyethylene sorbitol monooleate, and polyethylene glycol monooleate;stearic acid and other fatty acids; dicarboxylic acids; metal soaps;fatty acid amine salts; metal salts of heavy sulfonic acid; partialcarboxylic acid ester of polyhydric alcohol; phosphoric esters;(short-chain) alkenyl succinic acids; partial esters thereof andnitrogen-containing derivatives thereof; synthetic alkarylsulfonates,e.g., metal dinonylnaphthalene sulfonates; and the like and mixturesthereof.

Examples of friction modifiers include, but are not limited to,alkoxylated fatty amines; borated fatty epoxides; fatty phosphites,fatty epoxides, fatty amines, borated alkoxylated fatty amines, metalsalts of fatty acids, fatty acid amides, glycerol esters, boratedglycerol esters; and fatty imidazolines as disclosed in U.S. Pat. No.6,372,696, the contents of which are incorporated by reference herein;friction modifiers obtained from a reaction product of a C₄ to C₇₅,preferably a C₆ to C₂₄, and most preferably a C₆ to C₂₀, fatty acidester and a nitrogen-containing compound selected from the groupconsisting of ammonia, and an alkanolamine and the like and mixturesthereof.

Examples of antifoaming agents include, but are not limited to, polymersof alkyl methacrylate; polymers of dimethylsilicone and the like andmixtures thereof.

Each of the foregoing additives, when used, is used at a functionallyeffective amount to impart the desired properties to the lubricant.Thus, for example, if an additive is a friction modifier, a functionallyeffective amount of this friction modifier would be an amount sufficientto impart the desired friction modifying characteristics to thelubricant. Generally, the concentration of each of these additives, whenused, ranges from about 0.001% to about 20% by weight, and in oneembodiment about 0.01% to about 10% by weight based on the total weightof the lubricating oil composition.

The final application of the lubricating oil compositions of thisinvention may be, for example, in marine cylinder lubricants incrosshead diesel engines, crankcase lubricants in automobiles andrailroads and the like, lubricants for heavy machinery such as steelmills and the like, or as greases for bearings and the like. Whether thelubricating oil composition is fluid or solid will ordinarily depend onwhether a thickening agent is present. Typical thickening agents includepolyurea acetates, lithium stearate and the like.

In another embodiment of the invention, the lubricating oil additive ofthe present invention may be provided as an additive package orconcentrate in which the additive is incorporated into a substantiallyinert, normally liquid organic diluent such as, for example, mineraloil, naphtha, benzene, toluene or xylene to form an additiveconcentrate. These concentrates usually contain from about 20% to about80% by weight of such diluent. Typically a neutral oil having aviscosity of about 4 to about 8.5 cSt at 100° C. and preferably about 4to about 6 cSt at 100° C. will be used as the diluent, though syntheticoils, as well as other organic liquids which are compatible with theadditives and finished lubricating oil can also be used. The additivepackage will also typically contain one or more of the various otheradditives, referred to above, in the desired amounts and ratios tofacilitate direct combination with the requisite amount of base oil.

The following non-limiting examples are illustrative of the presentinvention.

EXAMPLE 1

Into a 500 ml, 3-neck round bottom flask equipped with an overheadmechanical stirrer, water condenser with nitrogen line and Dean-Starktrap, temperature controller, heating mantle, and thermocouple was added252 g of a polyisobutenyl succinic anhydride (PIBSA) having a 750 numberaverage molecular weight (Mn) polyisobutenyl group and a saponificationnumber (SAP) of 139 mgKOH/g. The mixture was heated to about 100° C. and47.3 g of tetraethylenepentamine (TEPA; 0.8 mole equivalent to PIBSA)was charged drop wise into the mixture via an addition funnel. Slightfoaming occurred during the initial charge stage. After the TEPA wascharged, the temperature was increased to 165° C. over about 60 minutesand was then held at 165° C. overnight.

The material was cooled and 50.00 g (0.0426 mol) was transferred to a250 ml three neck round bottom flask. The flask was heated at 100° C.for maleic anhydride addition. Next, 4.18 g of maleic anhydride (1 moleequivalent to TEPA) was added. The reactor temperature was increased to160° C. over an hour and then held at this temperature overnight.

The mixture was cooled to 85° C. and then 49.4 g of toluene, 6.12 g ofmolybdenum trioxide (1 mole equivalent to TEPA), 5 g of distilled water,and 2 drops of foam inhibitor were added. The mixture was stirred andheated at 100° C. overnight. The product was then filtered throughCelite 512 in a warmed Buchner funnel under vacuum. The filtrate wascollected and concentrated using a rotary evaporator (full pump vacuumat a maximum temperature of 140° C.) to remove toluene and residualwater. The product was a viscous brown oil and had the followingproperties:

Mo=2.35 wt. %

N=5.7 wt. %

Total Base Number=140 mg KOH/g

EXAMPLE 2

A molybdated succinimide complex was prepared using the same generalprocedure and components outlined in Example 1 except that thePIBSA:TEPA charge molar ratio was 0.5:1. The molybdated succinimidecomplex had a molybdenum content of 1.02 wt. %.

EXAMPLE 3

A molybdated succinimide complex was prepared using the same generalprocedure and components outlined in Example 1 except that the PIBSA hada 1000 Mn polyisobutenyl group and a SAP number of 120 mg KOH/g. Themolybdated succinimide complex had a molybdenum content of 5.9 wt. %.

EXAMPLE 4

A molybdated succinimide complex was prepared using the same generalprocedure and components outlined in Example 3 except that thePIBSA:TEPA charge molar ratio was 0.5:1. The molybdated succinimidecomplex had a molybdenum content of 0.4 wt. %.

EXAMPLE 5

A molybdated succinimide complex was prepared using the same generalprocedure and components outlined in Example 1 except that the PIBSA hada 2300 Mn polyisobutenyl group and a SAP number of 56.4 mg KOH/g. Themolybdated succinimide complex had a molybdenum content of 1.8 wt. %.

EXAMPLE 6

A molybdated succinimide complex was prepared using the same generalprocedure and components outlined in Example 5 except that thePIBSA:TEPA charge molar ratio was 0.5:1. The molybdated succinimidecomplex had a molybdenum content of 0.6 wt. %.

EXAMPLE 7

A molybdated succinimide complex was prepared using the same generalprocedure and components outlined in Example 3 except that thePIBSA:TEPA charge molar ratio was 1:1. The molybdated succinimidecomplex had a molybdenum content of 4.6 wt. %.

COMPARATIVE EXAMPLE A

A baseline lubricating oil formulation was formed containing 3.8 wt. %succinimide dispersant, 3.5 mM/kg low overbased calcium sulfonate, 45mM/kg highly overbased calcium sulfonate, 5 mM/kg zinc dithiophosphatederived from a secondary alcohol, 2 mM/kg zinc dithiophosphate from aprimary alcohol, 0.5 wt. % diphenylamine anti-oxidant, 0.3 wt. % pourpoint depressant, 4.8 wt. % olefin copolymer viscosity index improverand 10 ppm foam inhibitor in a Group II base oil.

COMPARATIVE EXAMPLE B

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example A. Acommercially available molybdenum oxide succinimide complex derived froma polyisobutenyl (1000 M.W.) was formulated into this baselinelubricating oil formulation such that the total Mo content in theformulation was 500 ppm.

EXAMPLE 8

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example A. Thelubricating oil additive of Example 1 was formulated into this baselinelubricating oil formulation such that the total Mo content in theformulation was 500 ppm.

EXAMPLE 9

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example A. Thelubricating oil additive of Example 2 was formulated into this baselinelubricating oil formulation such that the total Mo content in theformulation was 500 ppm.

EXAMPLE 10

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example A. Thelubricating oil additive of Example 3 was formulated into this baselinelubricating oil formulation such that the total Mo content in theformulation was 500 ppm.

EXAMPLE 11

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example A. Thelubricating oil additive of Example 4 was formulated into this baselinelubricating oil formulation such that the total Mo content in theformulation was 500 ppm.

EXAMPLE 12

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example A. Thelubricating oil additive of Example 5 was formulated into this baselinelubricating oil formulation such that the total Mo content in theformulation was 500 ppm.

EXAMPLE 13

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example A. Thelubricating oil additive of Example 6 was formulated into this baselinelubricating oil formulation such that the total Mo content in theformulation was 500 ppm.

EXAMPLE 14

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example A. Thelubricating oil additive of Example 7 was formulated into this baselinelubricating oil formulation such that the total Mo content in theformulation was 500 ppm.

Oxidation Performance

The effect of oxidation on the lubricating oil compositions of Examples8-14 containing the lubricating oil additive of the present inventionwere analyzed and compared to the effect of oxidation on the baselinelubricating oil formulation of Comparative Example A and the lubricatingoil composition of Comparative Example B in an oxidation bench test. Theoxidation studies were carried out in a bulk oil oxidation bench test asdescribed by E. S. Yamaguchi et al. in Tribology Transactions, Vol 42(4), 895-901 (1999). In this test, the rate of oxygen uptake at constantpressure by a given weight of oil at 170° C. was monitored. The timerequired to reach a period of rapid oxygen uptake, known asauto-oxidation, was designated as induction time. Bench test results aregenerally reproducible to within ±0.5 hours. In this test, the longerinduction time corresponds to more effective antioxidant. The oxidationbench test results are presented in Table 1.

TABLE 1 Oxidation Bench Test Results Comp. Ex. Ex. Mo Treat RateInduction Time Comparative Ex. A — 15 Comparative Ex. B 500 ppm 29Example 8 500 ppm 55 Example 9 500 ppm 25 Example 10 500 ppm 27 Example11 500 ppm 61 Example 12 500 ppm 30 Example 13 500 ppm 33 Example 14 500ppm 24As the data show, the lubricating oil compositions of this inventionwere comparable and, in some instances, significantly better thanlubricating oil compositions outside the scope of this invention.

COMPARATIVE EXAMPLE C

Into a 100 ml, round bottom flask equipped with a magnetic stirrer,water condenser with nitrogen line and Dean-Stark trap, temperaturecontroller, heating mantle, and thermocouple was added 25.1 g of acommercially available molybdenum oxide treated mono-succinimidedispersant prepared from polyisobutenyl (1000 M.W.) succinic anhydride(PIBSA) and a polyamine with about five amine groups per molecule having4.6% molybdenum and 2.2% nitrogen by weight. The charge mole ratio ofpolyamine:PIBSA was about 0.8:1. The molybdenum oxide treatedmono-succinimide dispersant was stirred and heated to 110° C. whileadding 1.68 g of maleic anhydride (1 mole equivalent). The mixture wasstirred at about 160° C. for 1 hour to yield a black viscous oil.

COMPARATIVE EXAMPLE D

Into a 100 ml, round bottom flask equipped with a magnetic stirrer,water condenser with nitrogen line and Dean-Stark trap, temperaturecontroller, heating mantle, and thermocouple was added 25.1 g of acommercially available molybdenum oxide treated mono-succinimidedispersant prepared from polyisobutenyl (1000 M.W.) succinic anhydride(PIBSA) and a polyamine with about five amine groups per molecule having4.6% molybdenum and 2.2% nitrogen by weight. The charge mole ratio ofpolyamine:PIBSA was about 0.8:1. The molybdenum oxide treatedmono-succinimide dispersant was stirred and heated to 110° C. whileadding 1.68 g of maleic anhydride (2 mole equivalents). The mixture wasstirred at about 160° C. for 1 hour to yield a black viscous oil.

COMPARATIVE EXAMPLE E

A baseline formulation was formed containing 5 wt. % succinimidedispersant, 3 wt. % borated succinimide dispersant, 4 mM/kg lowoverbased calcium sulfonate, 58 mM/kg carboxylate detergent, 8 mM/kgzinc dithiophosphate, 0.5 wt. % diphenylamine antioxidant, 0.5 wt. %hindered phenol anti-oxidant, 0.3 wt. % pour point depressant, 9.85 wt.% olefin copolymer viscosity index improver and 5 ppm foam inhibitor ina Group II base oil.

COMPARATIVE EXAMPLE F

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Acommercially available molybdenum oxide succinimide complex derived froma polyisobutenyl (1000 M.W.) was formulated into this baselinelubricating oil formulation such that the total Mo content in theformulation was 500 ppm.

COMPARATIVE EXAMPLE G

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Acommercially available molybdenum oxide succinimide complex derived froma polyisobutenyl (1000 M.W.) was formulated into this baselinelubricating oil formulation at 1 wt. %.

COMPARATIVE EXAMPLE H

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Thelubricating oil additive of Comparative Example C was formulated intothis baseline lubricating oil formulation such that the total Mo contentin the formulation was 500 ppm.

COMPARATIVE EXAMPLE I

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Thelubricating oil additive of Comparative Example C was formulated intothis baseline lubricating oil formulation at 1 weight percent.

COMPARATIVE EXAMPLE J

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Thelubricating oil additive of Comparative Example D was formulated intothis baseline lubricating oil formulation such that the total Mo contentin the formulation was 500 ppm.

COMPARATIVE EXAMPLE K

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Thelubricating oil additive of Comparative Example D was formulated intothis baseline lubricating oil formulation at 1 weight percent.

EXAMPLE 15

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Thelubricating oil additive of Example 1 was formulated into this baselinelubricating oil formulation at 500 ppm on a Mo basis.

EXAMPLE 16

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Thelubricating oil additive of Example 1 was formulated into this baselinelubricating oil formulation at 1 wt. %.

EXAMPLE 17

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Thelubricating oil additive of Example 2 was formulated into this baselinelubricating oil formulation such that the total Mo content in theformulation was 500 ppm.

EXAMPLE 18

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Thelubricating oil additive of Example 2 was formulated into this baselinelubricating oil formulation at 1 wt. %.

EXAMPLE 19

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Thelubricating oil additive of Example 3 was formulated into this baselinelubricating oil formulation such that the total Mo content in theformulation was 500 ppm.

EXAMPLE 20

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Thelubricating oil additive of Example 3 was formulated into this baselinelubricating oil formulation at 1 wt. %.

EXAMPLE 21

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Thelubricating oil additive of Example 4 was formulated into this baselinelubricating oil formulation such that the total Mo content in theformulation was 500 ppm.

EXAMPLE 22

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Thelubricating oil additive of Example 4 was formulated into this baselinelubricating oil formulation at 1 wt. %.

EXAMPLE 23

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Thelubricating oil additive of Example 5 was formulated into this baselinelubricating oil formulation such that the total Mo content in theformulation was 500 ppm.

EXAMPLE 24

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Thelubricating oil additive of Example 5 was formulated into this baselinelubricating oil formulation at 1 wt. %.

EXAMPLE 25

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Thelubricating oil additive of Example 6 was formulated into this baselinelubricating oil formulation such that the total Mo content in theformulation was 500 ppm.

EXAMPLE 26

A baseline lubricating oil formulation was formed containing the sameadditives, base oil and treat rate as in Comparative Example E. Thelubricating oil additive of Example 6 was formulated into this baselinelubricating oil formulation at 1 wt. %.

High Frequency Reciprocating Rig (HFRR) Evaluation

The HFRR wear and friction performance of the lubricating oilcompositions of Examples 15-26 of the present invention were evaluatedand compared to the baseline lubricating oil formulation of ComparativeExample E and the lubricating oil compositions of Comparative ExamplesF-K. The HFRR test is an industry recognized bench test for determiningthe valve train wear performance in candidate lubricating oils. The PCSinstrument uses an electromagnetic vibrator to oscillate a specimen (theball) over a small amplitude while pressing against a fixed specimen (aflat disk). The amplitude and frequency of the oscillation and the loadare variable. The frictional force between the ball and flat and theelectrical contact resistance (ECR) are measured. The flat, stationaryspecimen is held in a bath to which the lubricating oil is added, andcan be heated. The lubricating oils are pretreated with about 6% byweight, based on the total weight of lubricating oil, carbon black. Thecarbon black is stirred into the oil to wet it and then homogenized for15 minutes prior to testing. The wear scars on the balls are measuredmanually on an optical microscope and recorded. In this test, a smallerwear scar corresponds to a more effective anti-wear agent and a smallercoefficient of friction corresponds to a more effective frictionmodifier. The HFRR wear and friction performance data are presented inTable 2.

TABLE 2 HFRR Wear and Friction Performance Results Coefficient Comp.Ex./Ex. Concentration of Friction Wear Scar (μm) Comparative Ex. E —0.139 195 Comparative Ex. F 500 ppm 0.124 171 Comparative Ex. G 1 wt. %0.130 195 Comparative Ex. H 500 ppm 0.139 145 Comparative Ex. I 1 wt. %0.139 151 Comparative Ex. J 500 ppm 0.132 149 Comparative Ex. K 1 wt. %0.138 146 Example 15 500 ppm 0.081 158 Example 16 1 wt. % 0.124 182Example 17 500 ppm 0.133 195 Example 18 1 wt. % 0.136 211 Example 19 500ppm 0.140 135 Example 20 1 wt. % 0.132 137 Example 21 500 ppm 0.113 191Example 22 1 wt. % 0.137 193 Example 23 500 ppm 0.135 170 Example 24 1wt. % 0.138 150 Example 25 500 ppm 0.132 196 Example 26 1 wt. % 0.138173As the data show, the lubricating oil compositions of this inventionwere comparable and, in some instances, significantly better thanlubricating oil compositions outside the scope of this invention.

COMPARATIVE EXAMPLE L

Into a 500 ml, 3-neck round bottom flask equipped with an overheadmechanical stirrer, water condenser with nitrogen line and Dean-Starktrap, temperature controller, heating mantle, and thermocouple was added60.07 g of octadecenyl succinic anhydride (ODSA) (available from SigmaAldrich Corporation, St. Louis, Mo., U.S.A.), 60.08 g of Exxon 150neutral oil and three drops of foam inhibitor (200 to 350 cSt; availablefrom Dow Corning). The mixture was heated to 100° C. and 32.88 g oftetraethylenepentamine (TEPA; 1.0 mole equivalent to ODSA) was chargeddrop wise into the mixture via an addition funnel. Slight foamingoccurred during the initial charge stage. After the TEPA was charged,the temperature was increased to 160° C. over about 60 minutes and thenheld at 160° C. for three hours.

The material was cooled to less than 100° C. and 25.01 g of molybdenumtrioxide (1 mole equivalent to TEPA), 69 g of toluene, 17 g of distilledwater, and 0.1 g of foam inhibitor were added. The mixture was broughtto 100° C. and under agitation a gel formed with evolution of foam. 116g of Exxon 100N oil was added and the mixture was stirred overnight toyield a greenish brown gel. Accordingly, there was no attempt to reactthe gel with maleic anhydride.

COMPARATIVE EXAMPLE M

Into a 500 ml, 3-neck round bottom flask equipped with an overheadmechanical stirrer, water condenser with nitrogen line and Dean-Starktrap, temperature controller, heating mantle, and thermocouple was added60.6 g of a polyisobutenyl (1000 M.W.) succinic anhydride having a SAPnumber of 120.3 mgKOH/g. The mixture was heated to 100° C. and 10.45 gof tetraethylenepentamine (TEPA; 1.0 mole equivalent) was added. Afterthe TEPA was charged, the temperature was increased to 180° C. overabout 60 minutes and then held at 160° C. for one hour. After coolingovernight, 12.2 g of Exxon 100N oil was added to yield a viscous brownoil.

The material was heated to about 90° C. and 82 g of toluene was added toform a solution, followed by 7.9 g of molybdenum trioxide (1 moleequivalent to TEPA), and 8.3 g of distilled water. The mixture wasstirred at 90° C. for 1.5 hours and then the temperature was raised to160° C. and toluene and water were removed over about 4 hours. Theproduct was a viscous brown oil. Next, 64 g of toluene was added and themixture was heated to 95° C. to reduce the viscosity for filtration.Several attempts were made to filter the product through a Whatman brand#1 and #4 filter paper with and without diatomaceous earth filter aidwithout success. After repeated dilution of the product with Exxon 100Noil, the product could not be filtered. Accordingly, there was noattempt to react the product with maleic anhydride.

It will be understood that various modifications may be made to theembodiments disclosed herein. Therefore the above description should notbe construed as limiting, but merely as exemplifications of preferredembodiments. For example, the functions described above and implementedas the best mode for operating the present invention are forillustration purposes only. Other arrangements and methods may beimplemented by those skilled in the art without departing from the scopeand spirit of this invention. Moreover, those skilled in the art willenvision other modifications within the scope and spirit of the claimsappended hereto.

1. A molybdated succinimide complex prepared by a process whichcomprises (a) reacting a succinimide of a polyamine of formula I:

wherein R is a hydrocarbon radical having a number average molecularweight of about 500 to about 5,000, a and b are independently 2 or 3,and x is 0 to 10, with an ethylenically unsaturated dicarboxylic acidanhydride, in a charge mole ratio of the ethylenically unsaturateddicarboxylic acid anhydride to the succinimide of formula I of about0.9:1 to about 1.05:1; and (b) reacting the succinimide product of step(a) with an acidic molybdenum compound.
 2. The molybdated succinimidecomplex of claim 1, wherein R is a hydrocarbon radical having a numberaverage molecular weight of about 700 to about 2,500.
 3. The molybdatedsuccinimide complex of claim 1, wherein R is a hydrocarbon radicalhaving a number average molecular weight of about 710 to about 1,100. 4.The molybdated succinimide complex of claim 1, wherein R is apolyisobutenyl radical.
 5. The molybdated succinimide complex of claim1, wherein R is a polyisobutenyl radical having a number averagemolecular weight of about 700 to about 2,500.
 6. The molybdatedsuccinimide complex of claim 1, wherein R is a polyisobutenyl radicalhaving a number average molecular weight of about 710 to about 1,100. 7.The molybdated succinimide complex of claim 1, wherein a and b are each2, and x is 2 to
 5. 8. The molybdated succinimide complex of claim 4,wherein a and b are each 2, and x is 2 to
 5. 9. The molybdatedsuccinimide complex of claim 1, wherein the ethylenically unsaturateddicarboxylic acid anhydride is selected from the group consisting ofmaleic anhydride, citraconic anhydride, itaconic anhydride and mixturesthereof.
 10. The molybdated succinimide complex of claim 1, wherein theacidic molybdenum compound is selected from the group consisting ofmolybdenum oxide, molybdic acid, ammonium molybdate, sodium molybdate,potassium molybdates, hydrogen sodium molybdate, MoOCl₄, MoO₂Br₂,Mo₂O₃Cl₆, molybdenum trioxide and mixtures thereof.
 11. The molybdatedsuccinimide complex of claim 1, wherein the ethylenically unsaturateddicarboxylic acid anhydride is maleic anhydride and the acidicmolybdenum compound is molybdenum trioxide.
 12. The molybdatedsuccinimide complex of claim 4, wherein the ethylenically unsaturateddicarboxylic acid anhydride is maleic anhydride and the acidicmolybdenum compound is molybdenum trioxide.
 13. The molybdatedsuccinimide complex of claim 1, wherein the molar ratio of themolybdenum compound to the succinimide product of step (a) is about0.1:1 to about 2:1.
 14. The molybdated succinimide complex of claim 1,wherein the molar ratio of the molybdenum compound to the succinimideproduct of step (a) is about 0.5:1 to about 1.5:1.
 15. A process forpreparing a molybdated succinimide complex, the process comprising (a)reacting a succinimide of a polyamine of formula I:

wherein R is a hydrocarbon radical having a number average molecularweight of about 500 to about 5,000, a and b are independently 2 or 3,and x is 0 to 10, with an ethylenically unsaturated dicarboxylic acidanhydride, in a charge mole ratio of the ethylenically unsaturateddicarboxylic acid anhydride to the succinimide of formula I of about0.9:1 to about 1.05:1; and (b) reacting the succinimide product of step(a) with an acidic molybdenum compound.
 16. The process of claim 15,wherein R is a hydrocarbon radical having a number average molecularweight of about 700 to about 2,500.
 17. The process of claim 15, whereinR is a hydrocarbon radical having a number average molecular weight ofabout 710 to about 1,100.
 18. The process of claim 15, wherein R is apolyisobutenyl radical.
 19. The process of claim 15, wherein R is apolyisobutenyl radical having a number average molecular weight of about700 to about 2,500.
 20. The process of claim 15, wherein R is apolyisobutenyl radical having a number average molecular weight of about710 to about 1,100.
 21. The process of claim 15, wherein theethylenically unsaturated dicarboxylic acid anhydride is selected fromthe group consisting of maleic anhydride, citraconic anhydride, itaconicanhydride and mixtures thereof.
 22. The process of claim 15, wherein theacidic molybdenum compound is selected from the group consisting ofmolybdenum oxide, molybdic acid, ammonium molybdate, sodium molybdate,potassium molybdates, hydrogen sodium molybdate, MoOCl₄, MoO₂Br₂,Mo₂O₃Cl₆, molybdenum trioxide and mixtures thereof.
 23. The process ofclaim 15, wherein the ethylenically unsaturated dicarboxylic acidanhydride is maleic anhydride and the acidic molybdenum compound ismolybdenum trioxide.
 24. The process of claim 15, wherein the molarratio of the molybdenum compound to the succinimide product of step (a)is about 0.1:1 to about 2:1.
 25. The process of claim 15, wherein themolar ratio of the molybdenum compound to the succinimide product ofstep (a) is about 0.5:1 to about 1.5:1.
 26. A lubricating oilcomposition comprising (a) a major amount of a base oil of lubricatingviscosity; and (b) a minor amount of a molybdated succinimide complexprepared by a process which comprises (i) reacting a succinimide of apolyamine of formula I:

wherein R is a hydrocarbon radical having a number average molecularweight of about 500 to about 5,000, a and b are independently 2 or 3,and x is 0 to 10, with an ethylenically unsaturated dicarboxylic acidanhydride, in a charge mole ratio of the ethylenically unsaturateddicarboxylic acid anhydride to the succinimide of formula I of about0.9:1 to about 1.05:1; and (ii) reacting the succinimide product of step(i) with an acidic molybdenum compound.
 27. The lubricating oilcomposition of claim 26, wherein the base oil of lubricating viscosityis comprised of a mineral base oil.
 28. The lubricating oil compositionof claim 26, wherein R is a hydrocarbon radical having a number averagemolecular weight of about 700 to about 2,500.
 29. The lubricating oilcomposition of claim 26, wherein R is a hydrocarbon radical having anumber average molecular weight of about 710 to about 1,100.
 30. Thelubricating oil composition of claim 26, wherein R is a polyisobutenylradical.
 31. The lubricating oil composition of claim 26, wherein R is apolyisobutenyl radical having a number average molecular weight of about700 to about 2,500.
 32. The lubricating oil composition of claim 26,wherein R is a polyisobutenyl radical having a number average molecularweight of about 710 to about 1,100.
 33. The lubricating oil compositionof claim 26, wherein the ethylenically unsaturated dicarboxylic acidanhydride is selected from the group consisting of maleic anhydride,citraconic anhydride, itaconic anhydride and mixtures thereof.
 34. Thelubricating oil composition of claim 26, wherein the acidic molybdenumcompound is selected from the group consisting of molybdenum oxide,molybdic acid, ammonium molybdate, sodium molybdate, potassiummolybdates, hydrogen sodium molybdate, MoOCl₄, MoO₂Br₂, Mo₂O₃Cl₆,molybdenum trioxide and mixtures thereof.
 35. The lubricating oilcomposition of claim 26, wherein the ethylenically unsaturateddicarboxylic acid anhydride is maleic anhydride and the acidicmolybdenum compound is molybdenum trioxide.
 36. The lubricating oilcomposition of claim 26, wherein the minor amount of the molybdatedalkenyl succinimide complex is about 0.001 wt. % to about 10 wt. %,based on the total weight of the composition.
 37. The lubricating oilcomposition of claim 30, wherein the minor amount of the molybdatedalkenyl succinimide complex is about 0.001 wt. % to about 10 wt. %,based on the total weight of the composition.
 38. The lubricating oilcomposition of claim 26, further comprising at least one additiveselected from the group consisting of metallic detergents, ashlessdispersants, friction modifiers, extreme pressure agents, viscosityindex improvers and pour point depressants.
 39. The lubricating oilcomposition of claim 26, having a phosphorous content not exceeding 0.05wt. %, based on the total weight of the composition.
 40. The lubricatingoil composition of claim 26, having a sulfur content not exceeding 0.4wt. %, based on the total weight of the composition.
 41. A method ofoperating an internal combustion engine comprising the step of operatingthe internal combustion engine with the lubricating oil composition ofclaim
 26. 42. A method of operating an internal combustion enginecomprising the step of operating the internal combustion engine with thelubricating oil composition of claim 37.